[PATCH v1 17/27] ACPICA: Improve argument parsing in acpi_ps_get_next_simple_arg()

[Rafael J. Wysocki]

From: ikaros <void0red@xxxxxxxxx>

Improve argument parsing in acpi_ps_get_next_simple_arg() to handle
remaining AML data safely.

Link: https://github.com/acpica/acpica/commit/ecbb8bcfe301
Signed-off-by: ikaros <void0red@xxxxxxxxx>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
---
 drivers/acpi/acpica/psargs.c | 78 +++++++++++++++++++++++++++++++-----
 1 file changed, 68 insertions(+), 10 deletions(-)

diff --git a/drivers/acpi/acpica/psargs.c b/drivers/acpi/acpica/psargs.c
index 3526ea109414..064652d11d9a 100644
--- a/drivers/acpi/acpica/psargs.c
+++ b/drivers/acpi/acpica/psargs.c
@@ -384,6 +384,8 @@ acpi_ps_get_next_simple_arg(struct acpi_parse_state *parser_state,
 	u32 length;
 	u16 opcode;
 	u8 *aml = parser_state->aml;
+	u32 remaining = (u32)ACPI_PTR_DIFF(parser_state->aml_end, aml);
+	u64 partial_value;
 
 	ACPI_FUNCTION_TRACE_U32(ps_get_next_simple_arg, arg_type);
 
@@ -393,8 +395,13 @@ acpi_ps_get_next_simple_arg(struct acpi_parse_state *parser_state,
 		/* Get 1 byte from the AML stream */
 
 		opcode = AML_BYTE_OP;
-		arg->common.value.integer = (u64) *aml;
-		length = 1;
+		if (remaining >= 1) {
+			arg->common.value.integer = (u64)*aml;
+			length = 1;
+		} else {
+			arg->common.value.integer = 0;
+			length = 0;
+		}
 		break;
 
 	case ARGP_WORDDATA:
@@ -402,8 +409,19 @@ acpi_ps_get_next_simple_arg(struct acpi_parse_state *parser_state,
 		/* Get 2 bytes from the AML stream */
 
 		opcode = AML_WORD_OP;
-		ACPI_MOVE_16_TO_64(&arg->common.value.integer, aml);
-		length = 2;
+		if (remaining >= 2) {
+			ACPI_MOVE_16_TO_64(&arg->common.value.integer, aml);
+			length = 2;
+		} else {
+			arg->common.value.integer = 0;
+			length = 0;
+			if (remaining > 0) {
+				partial_value = 0;
+				memcpy(&partial_value, aml, remaining);
+				arg->common.value.integer = partial_value;
+				length = remaining;
+			}
+		}
 		break;
 
 	case ARGP_DWORDDATA:
@@ -411,8 +429,19 @@ acpi_ps_get_next_simple_arg(struct acpi_parse_state *parser_state,
 		/* Get 4 bytes from the AML stream */
 
 		opcode = AML_DWORD_OP;
-		ACPI_MOVE_32_TO_64(&arg->common.value.integer, aml);
-		length = 4;
+		if (remaining >= 4) {
+			ACPI_MOVE_32_TO_64(&arg->common.value.integer, aml);
+			length = 4;
+		} else {
+			arg->common.value.integer = 0;
+			length = 0;
+			if (remaining > 0) {
+				partial_value = 0;
+				memcpy(&partial_value, aml, remaining);
+				arg->common.value.integer = partial_value;
+				length = remaining;
+			}
+		}
 		break;
 
 	case ARGP_QWORDDATA:
@@ -420,8 +449,19 @@ acpi_ps_get_next_simple_arg(struct acpi_parse_state *parser_state,
 		/* Get 8 bytes from the AML stream */
 
 		opcode = AML_QWORD_OP;
-		ACPI_MOVE_64_TO_64(&arg->common.value.integer, aml);
-		length = 8;
+		if (remaining >= 8) {
+			ACPI_MOVE_64_TO_64(&arg->common.value.integer, aml);
+			length = 8;
+		} else {
+			arg->common.value.integer = 0;
+			length = 0;
+			if (remaining > 0) {
+				partial_value = 0;
+				memcpy(&partial_value, aml, remaining);
+				arg->common.value.integer = partial_value;
+				length = remaining;
+			}
+		}
 		break;
 
 	case ARGP_CHARLIST:
@@ -434,10 +474,28 @@ acpi_ps_get_next_simple_arg(struct acpi_parse_state *parser_state,
 		/* Find the null terminator */
 
 		length = 0;
-		while (aml[length]) {
+		while ((length < remaining) && aml[length]) {
+			length++;
+		}
+		if (length < remaining) {
+
+			/* Account for the terminating null */
 			length++;
+		} else {
+			/*
+			 * No terminator found - add null at buffer boundary
+			 * and report a warning
+			 */
+			ACPI_WARNING((AE_INFO,
+				      "Invalid AML string: no null terminator, truncating at offset %u",
+				      (u32)(aml - parser_state->aml)));
+
+			/* Add null terminator at the boundary */
+			if (remaining > 0) {
+				aml[remaining - 1] = 0;
+				length = remaining;
+			}
 		}
-		length++;
 		break;
 
 	case ARGP_NAME:
-- 
2.51.0